1. Field of the Invention
The present invention relates to a paper feeding device, an image forming apparatus, and a setting information switching method that enable switching of setting information concerning a sheet, and, more particularly to switching of series information concerning a sheet size.
2. Description of the Related Art
An inserter (a paper feeding device) connectable to an MFP (Multi Function Peripheral) is a device that inserts a front cover, insertion paper, a back cover, and the like in bookbinding.
The inserter includes plural sensors that detect the width and the length of a sheet in order to notify the MFP of a sheet size of a sheet set in a tray of the inserter. The inserter notifies the MFP of detected information concerning the sheet size. The MFP compares the notified information and sheet sizes of sheets (the sheet sizes are also detected by the sensors) set in paper feeding cassettes, paper feeding trays, and an ADF (Auto Document Feeder). When the sheet sizes mismatch, in order to prevent a poor finish of bookbinding (a bookbinding side is uneven because of the mismatch of the sheet sizes) and prevent paper jamming (in the case of an image forming apparatus having an automatic staple function, although sheets are aligned before stapling, paper jamming occurs when sheet sizes mismatch at this point), in general, the MFP performs control to prevent printing from being continued.
As the sheet sizes, there are series of sheet sizes such as an A4 size and a B4 size mainly used in Japan specified by the JIS standard (JIS: Japanese Industrial Standards) (hereinafter referred to as A series) and series of sheet sizes such as a Legal size and a Letter size mainly used in Europe and the United States (hereinafter referred to as LT series). For example, the A4 size (210 mm×297 mm) and the Letter size (216 mm×279 mm) are very close sheet sizes and A3 (420 mm×297 mm) and Ledger (432 mm×279 mm) are also very close sheet sizes. Differences in these sheet sizes also need to be detected for prevention of deficiencies in finish of bookbinding and prevention of paper jamming.
When the differences caused by the series are identified by sensors, a large number of sensors are necessary as shown in an inserter side view in FIG. 7 and an inserter plan view in FIG. 8 (e.g., to distinguish ten kinds of sheet sizes (B5-R, A4-R, LT-R, LG, B5, B4, LT, A4, LD, and A3), an inserter 300 needs at least seven sensors in total including six sheet width detection sensors 301 and one sheet length detection sensor 302). Since the sensors are required to have high position accuracy, manufacturing cost of the sensors is high.
There is also an inserter of a volume type (see FIG. 8) that reads, to read a sheet size, a voltage that varies in association with the width between sheet regulating plates 303 without using sheet size detection sensors for respective sizes and converts the voltage into a distance between the sheet regulating plates 303 to detect a sheet width size. However, like the mechanism for detecting sheet widths with the sensors, it is difficult to distinguish sheet sizes with the inserter of the volume type when sheet widths are close (e.g., the A4 size and the Letter size).
Therefore, in order to cause the MFP to determine the two series of close sheet sizes, i.e., the A series and the LT series, a user sets in advance, using a switch on an operation panel provided in the inserter or the MFP, whether sheet sizes are the A series or the LT series used in the inserter. However, the switching of the A series and the LT series by the switch has a problem in terms of convenience.